1. Field of the Invention
The present invention relates to an improvement in an arbitrary-direction tracer control unit which permits arbitrary setting of the tracer feed direction, and, more particularly, to an arbitrary-direction tracer control unit which allows an easy change of the tracer feed direction even during tracing.
2. Description of the Related Art
In arbitrary-direction tracing in which the tracer feed direction in an X-Y plane is a direction at an angle .alpha. (an A-axis) with respect to the X-axis as depicted in FIG. 5, tracer feed rates Va and Vz in the A-axis and the Z-axis are derived from a displacement signal available from a tracer head, operations Vx=Va.multidot.cos .alpha. and Vy=Va.multidot.sin .alpha. are conducted using the feed rate Va to obtain tracer feed rates Vx and Vz, and a model is driven in the X-, Y- and Z-axes at the speeds corresponding to the tracer feed rates Vx, Vy, and Vz.
Conventional arbitrary-direction tracer control equipment is of the type that prestores the angle .alpha. between the X-axis and the A-axis in a memory and performs the above-mentioned operations on the basis of the stored contents of the memory to obtain the feed rates in the X- and Y-axis directions; so the tracer feed direction cannot be changed unless the stored contents of the memory are changed. Accordingly, with the prior art equipment, it is difficult for an operator to change the tracer feed direction while monitoring the cutting conditions.